DTC Troubleshooting: P2646
DTC P2646: Rocker Arm Oil Pressure Switch Circuit Low Voltage
Special Tools Required
?Pressure Gauge Adapter 07NAJ-P07010A
?A/T Low Pressure Gauge w/Panel 07406-0070301
?A/T Pressure Test Hose 07AAJ-PY4A100
?A/T Pressure Adapter 07MAJ-PY40120
?Oil Pressure Hose 07ZAJ-S5AA200
NOTE:
Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information.
If DTC P2648 and/or P2649 are stored at the same time as DTC P2646, troubleshoot those DTCs first, then recheck for DTC P2646.

DTC Description
Confirmed DTC
Pending DTC
Freeze Frame
P2646 Rocker Arm Oil Pressure Switch Circuit Low Voltage
      

1.
Oil level check:

Oil level check
?1.
Check the engine oil level.

Is the level OK?

     
YES
     
     
     
Go to step 2.
     
NO
     
     
     
Adjust the engine oil to the proper level, then do the repair verification.
2.
Problem verification:

Problem verification
?1.
Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.

?2.
Select the VTEC TEST in the INSPECTION MENU with the HDS.

  

Is the result OK?

     
YES
     
     
     
Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the rocker arm oil pressure switch and the PCM.?
     
NO
     
     
     
The failure is duplicated. Go to step 3.
3.
Determine possible failure area (VTM line, Others):

Determine possible failure area (VTM line, Others)
?1.
Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.

?2.
Disconnect the following connector.

?3.
Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.

?4.
Check the parameter(s) below with the HDS.
Signal
Current conditions
Values
Unit
VTEC PRES SW
    

Is ON indicated?

     
YES
     
     
     
Go to step 5.
     
NO
     
     
     
Go to step 4.
4.
VTEC system oil pressure check:

VTEC system oil pressure check
?1.
Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.

?2.
Remove the rocker arm oil pressure switch (A) from the rocker arm oil control valve, and attach the special tools as shown, then attach the rocker arm oil pressure switch to the oil pressure gauge adapter (B).


?3.
Reconnect the rocker arm oil pressure switch 2P connector.

?4.
Start the engine.

?5.
Select the VTEC TEST in the INSPECTION MENU with the HDS.

  

?6.
Check the oil pressure.

Does the oil pressure increase to at least 392 kPa (4.0 kgf/cm2, 56.9 psi)?

     
YES
     
     
     
The VTEC system oil pressure is OK. Replace the rocker arm oil pressure switch, then do the repair verification.
     
NO
     
     
     
Inspect the VTEC system. If it is OK, replace the rocker arm oil control valve, then do the repair verification.
5.
Shorted wire check (VTM line):

Shorted wire check (VTM line)
?1.
Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.

?2.
Jump the SCS line with the HDS.


?3.
Disconnect the following connector.

?4.
Check for continuity between test points 1 and 2.
Test condition
IG LOCK (0) or OFF mode
 
Rocker arm oil pressure switch 2P connector: disconnected
 
PCM connector B (51P): disconnected
Test circuit
VTM
Test point 1
PCM connector B (51P) No. 21 (BLU/BLK)
Test point 2
Body ground


Is there continuity?

     
YES
     
     
     
Repair a short in the VTM wire between the rocker arm oil pressure switch and the PCM (B21), then do the repair verification.
     
NO
     
     
     
The VTM wire is OK. Update the PCM if it does not have the latest software, or substitute a known-good PCM, then do the repair verification.
Repair verification:

?1.
Reconnect all connectors.

?2.
Exit the SCS mode with the HDS.


?3.
Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.

?4.
Reset the PCM with the HDS.


?5.
Do the PCM idle learn procedure.

?6.
Select the VTEC TEST in the INSPECTION MENU with the HDS.

  

?7.
Check for Pending or Confirmed DTCs with the HDS.
DTC Description
Confirmed DTC
Pending DTC
Freeze Frame
P2646 Rocker Arm Oil Pressure Switch Circuit Low Voltage
      


Is DTC P2646 indicated?

     
YES
     
     
     
Check for poor connections or loose terminals at the rocker arm oil control solenoid and the PCM. If the PCM was updated, substitute a known-good PCM, then recheck. If the PCM was substituted, go to step 1.
     
NO
     
     
     
Troubleshooting is complete. If the PCM was substituted, replace the original PCM. If any other Pending or Confirmed DTCs are indicated, go to the indicated DTC's troubleshooting.?